Integrated circuit manufacturing techniques are now able to produces devices with feature sizes on the order of tens of nanometers. With these small feature sizes, material properties and quantum effects, which can be mostly ignored for larger devices, become more important and allow production of new types of devices. A SPASER, which gets its name from “surface plasmon amplification by stimulated emission of radiation” is a device that utilizes resonances of surface plasmons, which can arise on small metal regions. Surface plasmons themselves are giant oscillations of electron density at a surface of a material, typically a metal, which can be approximately modeled as a free electron sea in a compensating positive ionic background. When confined and not over damped, these surface plasmons are quantized and can have particle-like properties. Surface plasmons can also couple to or exchange energy with light modes and other electromagnetic radiation. In a SPASER, a pumping process increases the energy in a resonant mode of plasmons confined in a small region, so that the plasmons can create a large local electric field or emit electromagnetic radiation with a characteristic frequency that depends on the resonant mode of the plasmons.
Another device that has become practical through use of the properties of nanoscale materials is the memristor. U.S. Pat. App. Pub. No. 2008/0090337, entitled “Electrically Actuated Switch,” to R. Stanley Williams describes a switch that changes between a high-conductivity state and a low-conductivity state as a result of movement of dopants in thin layers of material. These switches can effectively act as resistors with memory (or memristors) having resistance that depends on the total dopant currents (and resulting dopant configuration) in the switches. Operation of the switches generally rely on behavior of nanoscale materials, particularly, the interaction of a primary material such as titanium dioxide (TiO2) and a source material such as oxygen depleted titanium dioxide TiO2-x that contains dopants (e.g., oxygen vacancies) that can move in response to an electric field. When the primary material and the source material are between two electrodes and a sufficient bias voltage is applied, charged dopant move between the primary material and the source material and can drastically change the electrical and optical characteristics of the primary material. For example, dopants flowing into an intrinsic primary material can make the primary material significantly more conductive, and dopant ions flowing out of the primary material can return the primary material to its intrinsic non-conductive state.
The pursuit of new devices employing the properties of nanoscale materials continues.
Use of the same reference symbols in different figures indicates similar or identical items.